As an LCF/commuter, I don't always get to decide when I ride, and sometimes it rains. To date, I'm perfectly happy with the Kenda Kwests I use - they have sufficient grip for how I alter my riding style when it's raining - but I'm considering alternatives. The Kendas are pretty much slicks until I'm at a lean angle I wouldn't use in the wet. Given the vanishingly-small contact patch of a bicycle tire, does tread really matter in wet/dirty (I don't ride off-pavement at all) conditions? Is it more about the tire compound?

My theory is no, the tires are just too narrow and the bike isn't moving fast enough to divert water away with the tread pattern. It's mostly just for show, I think.
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Tread actually does make a difference in the wet. Namely, it reduces traction by reducing contact area. Slicks with round profile are the way to go if you're staying on pavement. I've been very happy with Conti GP 4 Seasons and Schwalbe Marathon Supreme for wet use. Both are pricy but I don't think riding in the rain is a time to go cheap on tires. (Actually, I don't think any time is a good time to go cheap on tires, but in the rain I can use safety a an excuse.)

Thick rubber + puncture barriers add weight, but save time mending punctures
as a light supple fast, tire will, feel good , but perhaps.. succumb to road hazards.

Given how wet it's been in Shanghai this past 6 weeks or so, I'd like to say I'm VERY familiar (too familiar, in fact) with the riding characteristics of Kenda Kwests in the wet. And I'm really happy with them - if I were in your shoes, I wouldn't bother changing them. I've never found them to lack grip on even the wettest road/pavement surfaces.

I have to (respectfully) disagree with some opinions here. I've changed a number of tires sticking to the same size on all of them and I've seen major differences in how much grip or wet performance tires had in the rain. Some tires would lock up easier on braking, while others would side-slip with little effort. The worst tires (for rain) I've had on my bikes were Schwalbe Duranos and so far the best -by far- have been Michelin Pilot (Protek Max) which perform excellent in the wet.

In the winter I ride on Continental Security tires, very treaded and very flat resistant. And very high rolling resistance. But I don't like fixing flats in the dark on the way to work. I will be changing back to my slick tires soon, when I am riding in the daylight instead of the dark on my way to work. My wonderful city fathers don't sweep streets with no curb, and the longest stretch I have on the way to town has no curb and is often littered with flat-makers. But doing a lot of road riding in the rain on my road bike, I have not noticed any difference between those commute tires and my road tires as traction goes.

It makes no difference at all, except possibly degrading your traction if you do have tread.

Road surfaces themselves have quite a bit of "tread." Unless you're on loose stuff, the minimal tread found on a road-type tire isn't too relevant, certainly not for clearing water from under the contact patch. The road surface has enough negative space for that.

In the bigger picture, as a commuter, what you should be most concerned about in wet conditions is wet manhole covers and slick crosswalk stripes, that sort of thing.

I would say no, but tire manufacturers and the general public think otherwise. For me, bicycle tire tread is just small pebble magnet, with the slick tires that I've found are too soft of material to hold up to long term commuting, and are for higher speed cornering/traction. So far, the harder, durable, long wearing commute tires seem to come with some sort of tread pattern.

Painted surfaces are the worst when it rains. Also look out for wet railroad tracks.

In the rain the best thing is to lower the tire pressure a bit. You have about 50% less traction in the wet, so you do have to take it easy around corners.

On paved surfaces, the rubber compound/tire pressure probably has more to do with wet weather handling than tread pattern. Off road or loose surfaces is where tread patterns come in to play.

+1

Its not whether or not the tires have any kind of tread, its the characteristics of the rubber compound that affects dry/wet weather traction. Cheap tires have a hard dry compound and won't grip any surface well (i.e., Schwalbe Duranos), while good quality tires (i.e., Conti GP 4 Seasons) will grip well on any surface.

You really do what you pay for for the most part.

^^^ I agree with you, but I wouldn't call Duranos cheap tires. They're built for high mileage, and for that, you need a hard compound. Softer tires like GP 4 seasons or Marathon Supremes offer more traction on wet pavement, but you won't get as many miles out of them.

Disagree. My favorite commuting/training tire is the ~$20-25 (on sale) seca survivor. Its the functional equivalent of a gatorskin for half the cost.

Road Tread
https://i256.photobucket.com/albums/h...adtrash006.jpg

+1. I've read over and over people saying that tread doesn't help, a bald tire is "bitten into" by the pavement, etc. etc. but personal experience has just contradicted this on too many occasions for me to believe it. I prefer a treaded tire on wet surfaces -- I don't care what "should" happen. Though my personal "testing" is not scientifically sound, and has not been submitted for peer review, I've commuted enough miles now that I have a feel for "which tires will skid my ass into a ditch going around a wet curve" vs. ones that dont.

Note that I ride with fat tires, much larger than standard roadie tires. Obviously these grip better for the most part, but I have used skinnies for long periods of time and regardless of size, I still prefer a tire with tread for wet surfaces. YMMV.

I've put slick Schwalbe Ultremos 700/25 120psi on my new road bike and my first long ride happened to be in pouring rain. I had excellent traction, more than I expected. Not a single skid in 45 miles.

Anyone ever seen Formula 1 cars with threaded tires?

Yes , I think tire compound and size matter more than tread pattern. That said, my personal preference for my tires, I like a little inverse type pattern. I think they work better on those manhole, crosswalk type stuff. My commute also takes me on some dirt as well.

Yeah, I also believe it's the compound that matters most, not the thread.

Yes. Formula 1 has two sets of treaded tires. Intermediate and full wets.

Yes, but they're very fine, not deep like on most bicycle tires. Those deep threads on road bike tires only serve to make an impression on people.

They have more tread than you'd think for a race car.....

https://www.ausmotive.com/2011/03/25/...one-tyres.html

They are actually pretty wide tread patterns, but the mechanics of F1 tire in the wet are totally different than a bike tire.

The way I understand it, the weight per contact patch of a cycle tire is much greater and instead of hydroplaning on top of the water, a cycle tire would just cut right through it thus not needing tread pattern for clearing water from the track of the cycle.